A spirit of judgement and punishment
That very special day when the people try to use up all of the most horrible deaths for the coming year.
There are a lot of bad people out there. That is why we must torture you: to keep you safe.
Many and varied are the ways of extracting a confession or ending a criminal’s life, and the one usually follows the other.
Teenagers who run away from home to live in the wilderness may become feral. As they become more and more feral, they gain some supernatural powers (a la Peter Pan - ability to fly, things they imagine come true - possibly quite powerful), but at the expense of their humanity and ability to speak, comprehend complex subjects, etc. Maybe they have a leader: the most feral of them all.
A regression into a fantasy childlike state.